


The Downsides of Having a Teenage Baby Brother

by vaskianmountains



Category: Captive Prince - C. S. Pacat
Genre: (both chapters can be read separately if you only like one set of brothers), Alternate Universe - Modern Setting, Auguste (Captive Prince) Lives, Gen, Humor, M/M, Sex Education, and he will make sure his baby brother uses protection, now with a second part in which Kastor makes a reluctant attempt at being a decent older brother
Language: English
Status: Completed
Published: 2020-05-08
Updated: 2020-05-30
Packaged: 2021-03-02 18:15:04
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 1,841
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/24081166
Author URL: https://archiveofourown.org/users/vaskianmountains/pseuds/vaskianmountains
Summary: When Auguste first learned that Laurent had found himself a boyfriend, he was overjoyed. But his joy had been quick to turn to dread the moment he realized that teenagers possessed more hormones than sense.Kastor hadn’t come home for the weekend to deal with Damen and his new boyfriend, but he also didn’t want both of their moms and their dad to be disappointed in him.
Relationships: Auguste & Laurent (Captive Prince), Damen & Kastor (Captive Prince), Damen/Laurent (Captive Prince)
Comments: 48
Kudos: 300





	1. Auguste & Laurent

**Author's Note:**

> You can also find this ficlet on [tumblr](https://vaskianmountains.tumblr.com/post/617587427556589568/)

When Auguste first learned that Laurent had found himself a boyfriend, he was overjoyed. But his joy had been quick to turn to dread the moment he realized that teenagers possessed more hormones than sense.

Which was how he found himself standing in the intimacy isle at the drug store, because if there was even the slightest possibility that Damen and Laurent might end up having sex, then Auguste was going to make sure they were going to do so safely.

By now, Auguste had grown comfortable buying condoms. He knew which ones he preferred and worked best for him, and he knew what kind of lube to use with them. It usually didn’t take him more than a couple of minutes to grab what he needed and pay for them at the checkout.

But buying condoms for his baby brother was different. And he’d been staring for a while now at the shelves filled with a dozen brands that each had a dozen different options on offer. In fact, he’d just been standing there for so long that one of the store’s employees had come over to ask him if he needed any help.

“Oh no, I’m fine,” Auguste assured her. She didn’t look convinced, so he added, “Really, I’m right at home here!” Auguste wished he was at home. There really was no reason why he couldn’t have just ordered everything online.

He was told that if he changed his mind about needing help, he only needed to yell. He waited until she had left before turning back to his task.

It was just condoms. There was nothing scary or embarrassing about this. He took a deep breath, and picked standard lubed ones and placed them in his basket. Those should, in most circumstances, be perfectly able to do the trick. However, it would probably be better if Damen and Laurent had multiple options to choose from. So Auguste grabbed some more. Non-latex ones. Extra thin ones. Flavored ones. Colored ones, because why not? He was going to get anything that might make it more likely for Damen and Laurent to actually use protection. Which meant that—Auguste closed his eyes and steeled himself—he also made sure to grab extra large ones.

* * *

When Laurent got home, Auguste had already displayed everything he had bought on the dining table. The various condoms. Some dental dams. Multiple kinds of lube. He had very briefly wondered if he should also buy a dildo so they could practice putting on condoms before quickly dismissing the idea and trying to forget ever having thought of it. Buying condoms and lube for his baby brother so he could be safe was one thing, but buying sex toys was in another category entirely. (The drugstore, however, hadn’t agreed with Auguste, and they had placed them right next to the condoms. If they hadn’t, the mere idea would never have even crossed his mind, so he wasn’t the one to blame.) If they did actually need to practice putting on condoms, they probably still had a cucumber lying in the fridge.

The moment Laurent walked through the front door, Auguste came up to him and guided him to the dining table. “It’s time for a very important part of your upbringing,” he announced.

When Laurent saw the table full of condoms and realized what Auguste meant, he started protesting. “Auguste, we get taught sex ed in school. This really isn’t necessary.”

“Do they teach you sex ed, or do they teach you abstinence only?” Auguste asked.

“They teach us sex ed!”

“Does that include how to have safe non-heteronormative sex?”

Laurent didn’t answer that, so Auguste turned to the dining table again. He supposed that the condoms would be the most obvious place to start. He began with explaining how to take it out of the wrapper—“Don’t use your teeth!”—and with how to put it on. Laurent seemed to be following along well enough, so Auguste spared them both the suggestion that he should practice right there.

“You’ll find that with more experience, you’ll get more comfortable with putting it on. It might also take some trial and error to figure out what kind of condom works best for you, which is why I made sure to get you a variety of different options.” Yes, Auguste was going to commit to this. “You shouldn’t use one that’s too small. The band can get uncomfortable after a while, and if a condom gets stretched too much for too long the risk of it breaking might increase. But don’t get cocky,” Auguste immediately regretted his word choice, but thankfully managed to carry on like nothing had gone wrong. “If you use a condom that’s too big for you, there’s a risk of it slipping off, so making sure you’re using the right size is important.”

He took extra care to explain that protection should also be used during oral sex, because yes, if Auguste had to be entirely honest (and he wasn’t going to be to Laurent right now), he hadn’t always actually done so himself. That also meant stressing the importance of dental dams, and explaining how to make one out of a condom in case you didn’t have one on you.

With that done, Auguste turned to something equally important. “You need to make sure to use enough lube,” he said, “both because it will feel better and because if there is less friction the condom is less likely to break. When you think you’ve used enough, use some more.” Auguste went on to explain to not use oil based lube with latex condoms, and not to use silicone based lube if they used any silicone toys. “Which reminds me,” Auguste said. “If you’re sharing toys, you need to use condoms on those too. And when you switch between who uses them, you need to put a new one on them.” He hadn’t meant to talk about toys, but he supposed that a more comprehensive education on sex was always going to be better, anyway.

He looked at everything he had bought again, trying to see if he had missed anything. “I think that’s it!” he said. “The most important thing to remember is, of course, that sex is supposed to be fun, and that it should feel good for all of the people involved. If you ever feel uncomfortable, it’s important to say so. And if you feel like your boundaries are not being respected, you should try to get out.”

If Auguste had been presented with the option of keeping Laurent a child forever, he might have been tempted to take it. But he was going to have to accept that Laurent was growing into a man. Now, all he could do was to try and prepare Laurent for all aspects of life as best as he could, and hope that he had done well enough. “If you have any questions, you can always ask me. And if there’s anything concerning you right now, shoot.”

Laurent looked over everything on the table. He picked up a box labeled _Sized for a King: Extra Large_ , and pulled out a condom. As he circled the ring with his thumb, he said, “I’m not sure these are going to be big enough for Damen.”

**Notes for the Chapter:**

> Thank you for reading! I hope you enjoyed this. Comments and Kudos are always appreciated; they never fail to make my day 💖


	2. Kastor & Damen

**Summary for the Chapter:**

> Kastor hadn’t come home for the weekend to deal with Damen and his new boyfriend, but he also didn’t want both of their moms and their dad to be disappointed in him.

**Notes for the Chapter:**

> So I wrote a second part for this! This time it’s Kastor who has to deal with his teenage brother having just gotten a boyfriend. This one is much shorter than the Auguste & Laurent one, but then again, Kastor was never going to put as much effort into being a good older brother as Auguste. Also, as a quick note, this one is chronologically set before the Auguste & Laurent part. 
> 
> Like the previous part, you can also find this ficlet on [my tumblr](https://vaskianmountains.tumblr.com/post/619490857917333504/the-downsides-of-having-a-teenage-baby-brother)
> 
> I hope you enjoy this part too ❤️

Kastor sighed as the doorbell rang. Damen was still in the shower, and no one else was home to open the door. He was tempted to just ignore it, but there was only one person expected to visit them and both of their moms and their dad would both be sure to express their disappointment in him if he made Damen’s new boyfriend wait in front of a closed door. So, after sighing a second time, Kastor got up, walked downstairs, and opened the front door for his brother’s boyfriend.

Laurent was pretty. Flawless, clear skin that must have been the envy of all his classmates, and glowing golden hair. Kastor could understand why Damen had compared him to an angel. He wondered how correct Nikandros’ assessment had been when he pointed out that Lucifer was an angel too.

“Damen is taking a shower,” Kastor said, not bothering to introduce himself. If Damen’s gushing about how smart Laurent was had any truth to it, Laurent should be able to understand who Kastor was.

“I’ll wait in his bedroom for him then,” Laurent said.

“Sure,” Kastor said. He left Laurent at the door to come in himself and went back up to his own room. When he made to open his door, Laurent had followed him to the top of the stairs. That was also the exact moment that Damen stepped out of the bathroom. Completely naked.

In their family, nudity wasn’t something to be ashamed of, and it wasn’t uncommon to find one of them walking through the house without any clothes on, especially not after having just taken a shower. However, the important exception to that was when they had visitors over.

Laurent had flushed a bright pink, and he was staring straight at Damen’s crotch. “I see you are everywhere in proportion,” he said.

Laurent’s voice snapped Damen out of his shock, and he quickly brought his hands forward to cover himself. Kastor supposed that Damen was lucky that the men in their family were also blessed with big hands in addition to big dicks.

Damen’s eyes quickly darted to his bedroom door. “I’ll be back in a minute,” he said before scrambling inside and slamming the door shut behind him. Kastor was sure that the last time his brother’s voice had been that high was before he had entered puberty.

Next to him, Laurent swallowed. “I will wait downstairs, instead.”

Kastor felt tired. This wasn’t what he had come the weekend home for. He made a detour to the nightstand in his own room before knocking on Damen’s door.

“Just a minute!”

Kastor didn’t bother to wait.

Damen was sitting on his bed, now wearing a pair of boxers and a t-shirt that was inside out. His face had been buried in hands, but when he noticed the door opening, he had quickly shot up in a panic.

Kastor met Damen’s wide eyes. “Relax, it’s just me.”

“Kastor, what am I supposed to do now? I don’t know if I can still go downstairs and actually look Laurent in the eye.”

Kastor sat down next to Damen and patted him on the back. “It will be fine. You’re acting like no other guys have ever seen you naked, like you don’t regularly shower with other guys after sports.”

“But I’m not dating those guys!”

“You really don’t need to worry,” Kastor said. “It’s not about size or appearance. It’s the performance that counts. Even so, I don’t think Laurent was disappointed with what he saw. Also,” Kastor continued, and he pressed the condom he had taken from his nightstand into Damen’s hand, “you might not be able to get Laurent pregnant, but it’s still important to use protection.”

**Author's Note:**

> Thank you for reading! I hope you enjoyed this. Comments and Kudos are always appreciated; they never fail to make my day 💖


End file.
